Electronic equipment, such as that used in military applications, is often required to be operated in rugged, extreme environmental conditions. Examples of such conditions include excessive moisture, salt, heat, vibration, mechanical shock, and electromagnetic interference. To protect the generally fragile nature of the electronic equipment, the equipment is encased in sealed containers, essentially isolating the electronic equipment from the surrounding environment.
The sealed container, while effective at protecting the electronic equipment, exacerbates problems associated with removal of heat generated by operating the electronic equipment because there is little or no airflow for convection cooling. One common method of heat removal is the use of a heat sink to conduct heat away from the electronic equipment to the walls of the container which is then transferred to the surrounding environment by convection. In military applications, the heat sink is usually sandwiched between two printed circuit boards in accordance with MIL-STD-1389's Standard Electronic Module (SEM)-E.
To function cooperatively, some type of connector is required so that the two printed circuit boards are in electrical contact with one another and function as a single board when inserted into a backplane board or other module of a larger electronic piece of equipment.
Conventional connectors include a flexible, unitary connector having a U-shape that slides over each side of the circuit board/heat sink sandwich. This is undesirable for a number of reasons. The connector must be soldered to the board to make the connections, typically by hot bar soldering. This typically requires a tedious, time consuming process of making sure the connector is properly aligned with the boards. If the soldering is off by even a little bit, one or more of the circuits on the board may be discontinuous, leaving an open circuit. If the connector is misaligned or a circuit is damaged, the entire board, which is usually very expensive, must typically be scrapped. Further, these connectors are equipped with long tails to accommodate various sizes of circuit board/heat sink combinations, but which regularly extend to the board. As a result, the tails tend to act like antennae, creating interference that limits the speed at which the boards can operate to about 1 GB/sec or lower. Furthermore, as antennae, they may act as transmitters of interfering signals as well as receivers that may make the circuit susceptible to jamming.
Other conventional connectors include a two piece connector using so-called flex circuits extending from the printed circuit boards. Like the U-shape connector, these flex circuits must still be soldered to the printed circuit board. While the flex circuits may provide easier access for the soldering, similar problems of alignment are still presented. Like the U-shaped connector, the flex circuit has long tails that act like antennae, which create interference and limits performance as described above.
What is needed is a way to terminate the printed circuit boards for connecting to a larger backplane board that avoids problems associated with alignment in soldering a connector to the board and that eliminates or reduces interference associated with long tails extending through the printed circuit boards.